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Diverging Bar Chart

Source: R/plt-diverging-bar.R
diverging_bar_plt.Rd

Diverging Bars is a bar chart that can handle both negative and positive values. This can be implemented by a smart tweak with geom_bar(). But the usage of geom_bar() can be quite confusing. That's because, it can be used to make a bar chart as well as a histogram. Let me explain.

By default, geom_bar() has the stat set to count. That means, when you provide just a continuous X variable (and no Y variable), it tries to make a histogram out of the data.

In order to make a bar chart create bars instead of histogram, you need to do two things. Set stat = identity and provide both x and y inside aes() where, x is either character or factor and y is numeric. In order to make sure you get diverging bars instead of just bars, make sure, your categorical variable has 2 categories that changes values at a certain threshold of the continuous variable. In below example, the mpg from mtcars data set is normalized by computing the z score. Those vehicles with mpg above zero are marked green and those below are marked red.

Usage

diverging_bar_plt(
  .data,
  .x_axis,
  .y_axis,
  .fill_col,
  .plot_title = NULL,
  .plot_subtitle = NULL,
  .plot_caption = NULL,
  .interactive = FALSE
)

Arguments

.data

The data to pass to the function, must be a tibble/data.frame.

.x_axis

The data that is passed to the x-axis.

.y_axis

The data that is passed to the y-axis. This will also equal the parameter label

.fill_col

The column that will be used to fill the color of the bars.

.plot_title

Default is NULL

.plot_subtitle

Default is NULL

.plot_caption

Default is NULL

.interactive

Default is FALSE. TRUE returns a plotly plot

Value

A plotly plot or a ggplot2 static plot

Details

This function takes only a few arguments and returns a ggplot2 object.

See also

Other Plotting Functions: diverging_lollipop_plt(), gartner_magic_chart_plt(), los_ra_index_plt(), ts_alos_plt(), ts_median_excess_plt(), ts_plt(), ts_readmit_rate_plt()

Author

Steven P. Sanderson II, MPH

Examples

suppressPackageStartupMessages(library(ggplot2))

data("mtcars")
mtcars$car_name <- rownames(mtcars)
mtcars$mpg_z <- round((mtcars$mpg - mean(mtcars$mpg))/sd(mtcars$mpg), 2)
mtcars$mpg_type <- ifelse(mtcars$mpg_z < 0, "below", "above")
mtcars <- mtcars[order(mtcars$mpg_z), ]  # sort
mtcars$car_name <- factor(mtcars$car_name, levels = mtcars$car_name)

diverging_bar_plt(
  .data          = mtcars
  , .x_axis      = car_name
  , .y_axis      = mpg_z
  , .fill_col    = mpg_type
  , .interactive = FALSE
)